#3939 VFSBrowser absolute path completion doesn't wait for directory change

[Eric Le Lay]

When typing a full path in the VFS Browser open dialog filename, completion does expand the path, but still searches for files in the old directory.

org.gjt.sp.jedit.browser.VFSFileNameField.doComplete(String) calls TaskManager.waitForIoTasks() to no effect apparently.

Steps to reproduce:
1. prepare files
cd ~
touch a_test
cd /tmp
touch a.txt

1. in jEdit,
   File > Open (navigate to home directory if not already there)
   type /tmp/a in filename
   press TAB
   see that the filename is now /home/youruser/a_test and not /tmp/a